Where I come from, nobody cares all that much unless the issue of titles comes up. As Inquisitor and as a Comtesse, there was something of a dust-up when I got married because it complicates inheritance, but they were already flustered over my titles because I'm not human and it's a whole thing, so in the long run, it didn't matter much. The people in my mercenary band were mostly Tal-Vashoth or Vashoth (people of my race born outside the Qun, it's a long thing about philosophy but the Qun itself is hyper restrictive and forbids romantic and romance-based sexual relationships anyway) didn't care, either, because in throwing off the Qun, they discarded the Qun's views of sex and romance to start with. People have always been infinitely more concerned that I'm non-human and that I have magic; that I also exclusively prefer women and married one is more like a quirk that comes with the occasional inconvenience that basically nobody cares about.
So keep in mind that I come from what seems to be a unique position when I give you advice about this, yes? If you believe your friend may be discovering he's not interested in women, or not interested only in women, it may benefit you to just be upfront about it. If you tell him your opinion unprompted, it takes the pressure off of him to invite what, in his mind, may be a negative response.